1. Technical Field
The present invention relates to a headrest device, a headrest position adjusting method and a vehicle seat, and in particular, relates to a headrest device, a headrest position adjusting method and a vehicle seat that can automatically adjust the position of a headrest to an appropriate state.
2. Related Art
There have conventionally been proposed a headrest position adjusting device and headrest position adjusting method in which the electrostatic capacity between a headrest and the head portion of a person seated in a seat is measured by sensing electrodes that are disposed at the front surface side of the headrest over the entire region in the height direction thereof, and the position of the headrest is adjusted on the basis of the results of measurement (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2009-154551).
However, in the technique disclosed in JP-A No. 2009-154551, the electrostatic capacity between the head portion and the headrest is used in order to adjust the position of the headrest, and therefore, there is the problem that the cost is high. Further, while the electrostatic capacity is being measured, if there is a momentary movement of the head portion due to the driver confirming the region at the rear of the vehicle in the rear-view mirror or operating the car navigation device, or if there is continuous movement of the head portion due to vibration or the like, there are the problems that the measurement of the electrostatic capacity is unreliable and measurement requires a long time.